Hello,

I was on a Southwest 737-700 the other day and I noticed that after the pilots started engine 2 they turned the right pack on and then both packs on after both engines started. I normally only turn both packs on until both engines are started. I tried this different style with the pmdg ngx and it worked. Could anyone explain why this is done and if this is done on a normal basis?

 

Sam

If it's hot (or really cold) outside you can isolate engine 2 while starting 1 with the APU. The packs drive the air conditioning (and heating), and are much more effective at regulating temperature than the APU. The flight crew were doing you all a solid and getting the temperature back to where it should be, faster. It might be Southwest SOP to do that for all flights, or it could just be the habit of one of the flight crew. 

I guess that is the most probable reason why they did it. We departed from San Diego and it was extremely hot. I am travelling on a trip next week. I will try to see if the pilots do that again, or if it is just a one time thing for hot environments.